Design of Low Speed Axial Flux Permanent Magnet Generators for Marine Current Application. Sanjida Moury. Supervised by Dr.

Transcription

1 Design of Low Speed Axial Flux Permanent Magnet Generators for Marine Current Application Sanjida Moury Supervised by Dr. Tariq Iqbal Faculty of Engineering and Applied Science Memorial University of Newfoundland St. John s, NL, A1B 3X5, Canada October 16,

2 Presentation at a glance Objective Background Design challenges First prototype Minimization of Cogging Torque TORUS Configuration TORUS configuration Alternating Pole Arc Magnet Shifting Fractional Number of Slots Per Pole Generator design Rotor Stator Stator winding Prototyped Generator Test Result Mechanical Parameter test Electrical parameter test System model 2

3 Cont. Second prototype Generator Design Rotor Stator Stator winding Prototyped Generator Test Result Mechanical Parameter test Electrical parameter test System model Comparison between two prototype Conclusion Future work Acknowledgement 3

4 Objective To extract few watts electrical power from the sea-floor ocean current. To design a generator suitable for under water application. To design a direct driven generator by eliminating step-up gearbox. To design permanent magnet generators as a low speed energy converter. 4

5 Background Permanent Magnet Generator (PMG) Figure 1(a): Radial Flux PMG Figure 1(b):Axial Flux PMG 5

6 Background (Cont.) Axial Flux PMG Figure 2:Different types of AFPMG 6

7 Background (Cont.) AFPM disc-type motor structures Figure 3: (a) slotless TORUS, (b) slottedtorus, (c) slotless AFIR, and (d) slotted AFIR machines. 7

8 Design Challenges No of pole T max L m 1 L s 1 p 2 L = s L + m n L σ f = 120 p Size Material Air gap 8

9 First Prototype Figure 4: Designed generator 9

10 Minimization of Cogging Torque Torque Components 1. Torque Ripple 2. Cogging Torque 3. Pulsating Torque Minimization technique 1. Reducing the amplitude of each portion 2. Shifting the relative phase of the different components 10

11 Minimization of Cogging Torque (Cont.) TORUS Configuration (a) (b) Figure 5: TORUS Topology (a) NN type and (b) NS type 11

12 Minimization of Cogging Torque (Cont.) Alternating Pole Arc Figure 6(a): Same magnet pole arc Figure 6(b): Different magnet Pole arc 12

13 Minimization of Cogging Torque (Cont.) Magnet Shifting Fractional Number of Slots Per Pole Figure 7: Axial view of Rotor With Shifted magnet Figure 8: Two dimensional view of shifted magnet 13

14 Generator Design Rotor Magnetic material- NdFeB Number of pole- 100 Large magnet Large gap Steel ring Small gap Small magnet Figure 9: Full and sectional view of Rotor 14

15 Generator Design (Cont.) Stator Slotted stator is build with ferrite E-cores. (a) (b) Figure 10: (a) E-core (b) Stator 15

16 Generator Design (Cont.) Stator Winding Number of turns Emax 2π E rms = = N f ϕ max 2 2 N N s ph ϕ = A magn max B max B max = B r ( l m lm + δ ) 16

17 Generator Design (Stator Winding) Cont Figure 11: Prototyped stator 17

18 Generator Design (Stator Winding) Cont Figure 12: Stator winding 18

19 Prototyped Generator Figure 13: prototyped generator 19

20 Test result Mechanical Parameter test r Rotor J = mr 2 2 m F Figure 14: Initial torque Measurement 20

21 Test result (cont.) Electrical parameter test Generator Multimeter Oscilloscope Load Prime mover Figure 15: Test setup 21

22 Test result (Electrical parameter test) cont. Figure 16: Open Circuit voltage characteristic 22

23 Test result (Electrical parameter test) cont. Each graph shows the variation of generated power with rotational speed. The different graphs are for different load (2-20 ohm). Figure 17: Output Characteristic 23

24 Test result (Electrical parameter test) cont. The graph shows the variation of load voltage with load current as load varies from 0-20 ohm. The different graphs are for different frequencies. Figure 18:Load current and voltage characteristic 24

25 Test result (Electrical parameter test) cont. Each graph shows the variation of generated power with load. The different graphs are for different frequencies. Figure 19: Load characteristic 25

26 Test result (Electrical parameter test) cont. The voltage wave form for the both sides of the stator Resultant wave form after connecting the both sides of the stator in series Figure 20: Voltage wave form 26

27 System model Internal resistance, R g, [ohm] 1.8 Internal inductance, L g [µh] Machine constant, λ m No load loss. R null [ohm] 0.003f f Inertia, J m [Kg-m 2 ] o.96 Initial torque, T o [N-m] 14.5 Open Circuit voltage at 72 rpm [volt] 5.18 Figure 21: System model Load for maximum power point [ohm]

28 Conclusion Output Power is 3.5 watt at 72 rpm. Open circuit voltage is 5.2 volt at designed speed. Generating current is high due to thicker wire. Cogging torque is minimized. Large in size More frictional loss 28

29 Second Prototype Figure 22: Designed generator 29

30 Generator design PCB stator Figure 23: Designed topology of second prototype 30

31 Generator design (cont.) Rotor Figure 24: Rotor 31

32 Generator design (Rotor )cont. Figure 24: Rotor 32

33 Generator design (cont.) Stator Figure 25: 4 layer PCB Stator 33

34 Generator design (cont.) Stator Winding Figure 26: Stator Winding Pattern Figure 27: Stator winding 34

35 Generator design (Stator winding) cont. Figure 28: A single winding with dimension (in Inches) 35

36 Prototyped generator Figure 29: Prototyped Generator 36

37 Test Result Stress and strain test Figure 30: Stress strain test result 37

38 Test Result (Cont ) Mechanical parameter test N1= No (1-e t1/bj ) Figure 31: Friction loss test result 38

39 Test Result (Cont ) Electrical parameter test Figure 32: Test setup 39

40 Test Result (Electrical parameter test) Cont. Figure 33: Open Circuit voltage characteristic 40

41 Test Result (Electrical parameter test) Cont. Each graph shows the variation of generated power with rotational speed. The different graphs are for different load (2-20 ohm). Figure 34: Output Characteristic 41

42 Test Result (Electrical parameter test) Cont. The graph shows the variation of load voltage with load current as load varies from 0-20 ohm. The different graphs are for different frequencies. Figure 35:Load current and voltage characteristic 42

43 Test Result (Electrical parameter test) Cont. Each graph shows the variation of generated power with load. The different graphs are for different frequencies Figure 36: Load characteristic 43

44 Test Result (Electrical parameter test) Cont. Figure 37: Voltage wave form 44

45 System parameter Internal resistance, R g, [ohm] 4.4 Internal inductance, L g [µh] 66.2 Machine constant, λ m No load loss. R null [ohm] f f Inertia, J m [Kg-m 2 ] Friction, B m 0.3 Initial torque, T o [N-m] 0 Open Circuit voltage at 72 rpm [volt] 5.6 Load for maximum power point [ohm]

46 Conclusion Small in size No cogging Less friction Zero initial torque Higher voltage, 5.6 volt at 72 rpm. Less current and power (1.8 watt) 46

47 Comparison between two prototype Size Output Torque Manufacturing process 47

48 Conclusion Two prototypes are built and tested. First Prototype New cogging torque minimization technique More power Larger size Higher current Lower voltage Second prototype PCB stator Smaller size Higher voltage Lower current and power 48

49 Future Work Air gap reduction Material choice Smaller E-core More layer PCB Optimization 49

50 Acknowledgement Dr. Tariq Iqbal Seaformatics group Atlantic Innovation Funds ( Memorial University of Newfoundland All of my friends and family 50

51 THANKS? Questions 51

52 Magnet properties 52

53 RENSHAPE 440 material properties 53

54 Properties of AWG 20 54

55 Rotor Yoke (mild steel C-1020) data 55

56 FR-4 data 56

57 Generator design parameters 57

58 Generator design parameters 58